Plain Abdominal Radiography

Massive dilation of the sigmoid colon loop arising from the pelvis and extending to the diaphragm is a typical finding of sigmoid volvulus. The walls of the loop are evident as three bright lines converging in the pelvis to create a beaklike appearance (see the image below).

Cecal volvulus produces large- and small-bowel obstruction. Radiographic findings reveal a markedly distended loop of bowel extending from the right lower quadrant upward to the left upper quadrant. The small bowel is distended, whereas the distal colon is decompressed (see the image below).

CT of Abdomen and Pelvis

Computed tomography (CT) is not often needed, because the plain radiographic findings typically suffice for diagnosis of sigmoid volvulus. However, the radiographic findings for cecal volvulus may be less diagnostic. In such cases, CT can delineate the exact site of the torsion and reveal evidence of ischemia.

Upward displacement of the appendix with large-bowel obstruction is a definitive sign of cecal volvulus. Additionally, decompressed transverse and descending colon are apparent.

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Barium Enema

A contrast enema should be performed in patients who show no evidence of peritonitis and in whom plain abdominal radiographs are not diagnostic. The contrast study typically demonstrates a beaklike termination at the point of the sigmoid volvulus (see the image below). Similarly, a foldlike termination may be observed at the point of obstruction in the ascending colon in patients with cecal volvulus.

Barium enema of sigmoid volvulus revealing termination of contrast in bird's-beak formation at base of volvulus.

Cecal volvulus with ischemic changes of distended cecum and terminal ileum. Remainder of small bowel involved in volvulus appears distended but not ischemic. No obvious peritoneal contamination is observed.